The present invention relates to a scroll type compressor. Particularly, the present invention pertains to structures of a fixed scroll and a movable scroll used in a scroll type compressor.
A typical scroll type compressor has a fixed scroll and a movable scroll in a housing. The fixed scroll includes a fixed base plate and a fixed volute portion, which is formed on the fixed base plate. The fixed volute portion has a proximal end and a distal end relative to the fixed base plate. The movable scroll includes a movable base plate and a movable volute portion, which is formed on the movable base plate. The movable volute portion has a proximal end and a distal end relative to the movable base plate. The fixed scroll is engaged with the movable scroll. A number of compression chambers are formed between the fixed scroll and the movable scroll. When the movable scroll orbits the axis of the fixed scroll, each compression chamber moves from the peripheral portion (or outside portion) of the fixed volute portion toward the center of the fixed volute portion. Gas drawn into each compression chamber from the peripheral portion of the fixed volute portion is gradually compressed as the compression chamber moves.
When the scroll type compressor is operated, each proximal end portion of the fixed volute portion and the movable volute portion receives a bending moment repeatedly. The bending moment promotes deterioration of the scrolls. This shortens the life of the compressor. Therefore, a compressor that prevents the scrolls from being deteriorated and maintains the compression performance has been proposed in a prior art disclosed in, for example, Japanese Laid-Open Patent Publication No. 10-141255.
FIG. 5 is an enlarged partial cross-sectional view illustrating a fixed scroll 1 and a movable scroll 2 of the above publication. The fixed scroll 1 has a fixed volute portion 6 and the movable scroll 2 has a movable volute portion 8. The fixed volute portion 6 has proximal end corners 6b and distal end corners 6c. The movable volute portion 8 has proximal end corners 8b and distal end corners 8c. The proximal end corners 6b of the fixed volute portion 6 and the proximal end corners 8b of the movable volute portion 8 are arched to prevent the concentration of stress. This shape increases the fatigue strength under the bending moment generated when the compressor operates. Each distal end corner 6c of the fixed volute portion 6 is chamfered not to interfere with the corresponding proximal end corner 8b of the movable volute portion 8. The fixed volute portion 6 and the movable volute portion 8 define a compression chamber 15, which has a predetermined volume. A first chip sealing 17 is located on the distal end of the fixed volute portion 6. A wear-resistant plate 21, which is made of metal, is located on a bottom surface 5a between adjacent parts of the fixed volute portion 6. The wear-resistant plate 21 contacts a second chip sealing 18, which is arranged on the distal end portion of the movable volute portion 8. The wear-resistant plate 21 is spaced from the distal end portion of the movable volute portion 8. The distance between the wear-resistant plate 21 and the distal end portion of the movable volute portion 8 is equivalent to the length of the part of the second chip sealing 18 that protrudes from the distal end portion. Therefore, the distal end corners 8c of the movable volute portion 8 are not chamfered. This structure permits the compression chamber 15 to be reliably sealed. Thus, the scroll type compressor is smoothly operated.
An air conditioning apparatus for vehicles these days is required to have a reduced size and weight and to have a compression mechanism that discharges highly pressurized gas. However, some parts in a compressor are made of aluminum to reduce weight. Thus, a compression mechanism must have improved durability against the high pressure. Furthermore, a prior art sealing method is insufficient and improvement of the sealing is also desired.
Specifically, the fixed volute portion 6 and the movable volute portion 8 illustrated in FIG. 5 are plate-like and have a substantially uniform thickness. Thus, if the thickness of the fixed volute portion 6 and the movable volute portion 8 is reduced for reducing weight, the thickness of each proximal end portion of fixed volute portion 6 and movable volute portion 8 is not enough. Thus, the strength of each proximal end portion is insufficient. When the first chip sealing 17 is fitted to the distal end portion of the fixed volute portion 6, the thickness of the distal end portion needs to be the sum of the width a of the first chip sealing 17 and the thickness b of the outer wall multiplied by two required to support the first chip sealing 17. For example, when the curvature of the proximal end corners 8b of the movable volute portion 8 is increased to increase the strength, the curvature of the distal end corners 6c of the fixed volute portion 6 needs to be increased accordingly. As a result, the thickness of the fixed volute portion 6 is increased.
The position of the wear-resistant plate 21 is determined by two positioning pieces 20 with respect to the fixed scroll 1. However, each positioning piece 20 deforms the fixed volute portion 6 or damages the wall of the fixed volute portion 6.
Gas flows between a space between the distal end surface of the movable volute portion 8 and the surface of one of the positioning pieces 20 that faces the distal end surface of the movable volute portion 8, and a space between the positioning piece 20 and the corresponding proximal end corner 6b. Therefore, the gas could leak from the compressor.
The objective of the present invention is to provide a scroll type compressor that is reduced in weight and size and has great fatigue strength and a scroll that is sufficiently sealed.
To achieve the foregoing objective, the present invention provides a scroll type compressor for compressing gas. The compressor includes a fixed scroll, a movable scroll, a compression chamber, and a plurality of sealing members. The fixed scroll includes a fixed base plate and a fixed volute portion, which is formed on the fixed base plate. The fixed volute portion is tapered and the corners of the proximal end of the fixed volute portion are arched. The movable scroll is arranged to be engaged with the fixed scroll. The movable scroll includes a movable base plate and a movable volute portion, which is formed on the movable base plate. The movable volute potion is tapered and the corners of the proximal end of the movable volute portion are arched. The compression chamber is defined between the fixed scroll and the movable scroll. The compression chamber moves from the peripheral portion of the fixed volute potion toward the center as the movable scroll orbits the axis of the fixed scroll. One of the sealing members is located on the fixed base plate and the other
of the sealing members is located on the movable base plate.
Other aspects and advantages of the invention will become apparent from the following description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention.